SEOUL, South Korea -- North Korean state media is reporting that the regime's military leaders are demanding that South Korea apologize for protests against the North, and are warning of striking without notice.

Meanwhile, South Korean and U.S. forces remain on high alert for any provocation.

One North Korean defector, identified only as Mr. Bae for his protection, told CBN North Korea's threats are very familiar to him.

"From my early childhood days, preschool days, I was taught that my number one enemy was the United States," Bae recalled. "We lived in constant state of war. Two or three times a year the government announced it was going to attack our enemies."

Bae is reportedly one of a few third-generation North Korean Christians known to have defected to South Korea. His life as a secret believer inside the reclusive communist nation is detailed in the book, These Are The Generations.

"Your life is marked with risk the moment you decide to accept Jesus Christ as savior," he said. "That's the price you pay for being a member of the underground Church."

It's a price that he and his family have paid. Bae was arrested without charge for more than a year on suspicion of Christian activity.

"My entire family, including my children and parents, were always evangelizing," Mr. Bae said. "Of course, we did this in secret and we had to be careful. But the authorities became suspicious."

He was eventually released from prison without being charged. Bae says that was a miracle. But others weren't that fortunate. Several members of his family, including his mother and brothers, are in a North Korean concentration camp because of their own evangelistic activity.

"They were sent to a concentration camp because the authorities found a Bible and several evangelistic pamphlets in the house," Bae told CBN News.

Some 200,000 prisoners are being held in political prison camps in North Korea. An estimated 30,000 of them are Christians.

Bae now works to see his country won for Christ. He advises Eric Foley, an American who's living in Seoul and helping train defectors to effectively share the Gospel.

"Eighty percent of North Korean defectors are in regular contact with family members still inside North Korea," Foley said. "That means that the frontline in North Korean ministry isn't on the border with China, it is right here in Seoul."

In a non-descript building not too far from Seoul's city center, Foley holds regular evangelistic classes for North Koreans who've defected to South Korea. He considers these men and women highly strategic for reaching North Koreans around the world with the Gospel.

"North Korea maintains large contracts with Russia, Mongolia and China where workers are sent abroad for one to 10 years," Foley explained. "So North Korean defectors actually can reach their family members not only by going back inside North Korea, but even by going to China, Russia, Mongolia, South East Asia."

Bae and Foley say the best way to pray for North Korea during these tense times is to remember the underground believers who work quietly in the shadows.

"They are the faithful ones who endure so much to share Jesus," Bae said. "Please pray that God will give them strength and more boldness."

Foley added, "What is most impressive is that that work doesn't change even in the last month when Kim Jung Un rattles his sabre. The North Korean Church is still focused on being faithful in propagating the Gospel."